Abstract 10260: Anti-atherogenic Properties of the Orally Active Adenosine A2A Receptor Agonist ATL313.
Introduction: Adenosine A2A receptor (A2AR) activation mediates anti-inflammatory and anti-aggregatory changes in the vasculature. We previously showed potent anti-atherosclerotic effects of A2AR stimulation including inhibition of macrophage foam cell transformation and upregulation of the reverse cholesterol transport proteins cholesterol 27-hydroxylase and ATP binding cassette transporter (ABC) A1. Until recently, major obstacles to clinical use of A2AR agonists included lack of selectivity over other adenosine receptor subtypes and short half-life. ATL313, a new A2AR ligand, is selective, orally bioavailable, efficacious and long acting.
Methods and Results: THP-1 human monocytes/macrophages, a pertinent model of atherosclerosis, were incubated ± ATL313 (18h, 10 nM) ± 1h pre-incubation with the A2AR antagonist ZM-241385 (1 μM). Gene expression was evaluated by real-time PCR. THP-1 differentiated macrophages (phorbol dibutyrate) were lipid-loaded (acetylated LDL, 50μg/ml, 48h). Foam cell formation was quantified as percent Oil red O stained cells. Studies were done in triplicate. ATL313 exerted powerful anti-atherogenic effects on THP-1 monocytes/macrophages. In monocytes, ATL313 upregulated 27-hydroxylase and ABCA1 message (179.5± 10.1% and 245.6± 28.3% of untreated control [set at 100%], respectively (P<0.001). Pre-incubation with ZM-241385 nullified the ATL313 effect on 27-hydroxylase and ABCA1 (53.5± 3.2% and 40.7± 3.5% of control respectively, P<0.01). ATL313 induced downregulation of CD36 and this effect was blocked by ZM-241385 (73.2±2.6% of untreated control [set at 100%] for ATL313 alone vs. 157.9±6.2% for ATL313 + ZM-241385, P<0.01). Western blot analysis confirmed PCR results. We verified that ATL313 attenuation of foam cell formation is mediated through the A2AR by showing a 216.47% increase in foam cells when ATL313-treated cells were pre-exposed to ZM−241385. ATL313 alone yielded 28.29±3.48% foam cells vs. 61.24±5.39 % for ZM-241385 + ATL313.
Conclusions: ATL313 is an anti-atherogenic agent that prevents lipid overload via effects on cholesterol transport. Novel therapeutic approaches to increased cardiovascular risk may be directed toward improved cholesterol balance through A2AR activation.
- © 2010 by American Heart Association, Inc.